1. Field of the Invention
The invention relates to the field of vortex chamber valves for liquids in general, and in particular, to such a valve having a vortex chamber, at least one inlet nozzle which issues substantially tangentially into the chamber and one substantially central outlet nozzle.
2. Prior Art
Compared with conventional types of valves, vortex chamber valves have the advantage of operating without moving mechanical parts. Due to the fact that they are essentially free from wear and maintenance they provide an extremely high operating reliability. Due to these advantages they are used where it is necessary to control fluids which are difficult to handle and where extreme conditions are placed on the operational reliability. Fluids which are difficult to handle are corrosive, radioactive or hot gases or liquids used in chemical and physical processes, as well as sewage and sludge conveying contaminants and fibrous materials. A high operational reliability is particularly required, for example, in the protection and operation of nuclear power stations. In hydraulic structures the automatic control of discharges and runoffs from storage basins, flood basins, settling tanks and the like requires valves which are able to reliably start operating after being shut down for many years and carry away very coarse contaminants.
Special vortex chamber valves have been developed for use in hyraulic structures which are able to operate with very small control pressures (low pressure valves). These valves make it possible to branch off the control pulse from the main stream or flow to be controlled. Hitherto two types of such valves have been developed to a level permitting their practical use, namely radial vortex chamber valves or radial amplifiers (cf DOS No. 2 035 580) and axial vortex chamber valves or axial amplifiers (cf German Pat. No. 2 431 112).
If only the supply current flows with respect to the valves a relatively loss-free lowering flow takes place. If in addition a flow is passed through the tangential control nozzle a momentum is imparted to the fluid in the chamber which leads to a helical flow. This helical flow leads to the velocity of the flow being greatly increased towards the outlet, which in turn causes centrifugal forces so that the flow through the valve is greatly constricted. With a slight control overpressure, the supply flow can be virtually stopped. The valves function in a flow-increasing manner if a control flow simultaneously acts on tangential control nozzles which are oppositely directed in pairs. The vortex formed when action takes place on only a single nozzle is blown down again by the second nozzle.
However, both the radial valve and the axial valve have certain qualities which restrict their use under certain conditions. The disadvantage of the radial valve is that eddies are formed in the vortex chamber even without a control flow and these produce pressure losses and reduce the throughflow. Thus, limits are placed on the control range or efficiency of the valve. Due to the uniform annular axial feed for the supply flow in the case of axial amplifiers, asymmetrical flow states no longer occur, so that a very uniform sink flow is obtained without a control flow. Thus, the pressure losses are smaller than with the radial amplifier. However, compared with a tubular control nozzle, the annular construction thereof increases the danger of clogging or blockage if liquids with coarse impurities are to be passed through the valve.